Diversity. We celebrate it, exploring the food, music and clothing of new cultures. Lunch with someone from elsewhere makes us feel well-traveled.

We’re not fans of diversity though, when it’s invisible. Whether or not there’s a noticeable contrast of melatonin or accent, it’s our instinct to bridge the diversity divide by mirroring one another’s facial and vocal expressions. We relish the things we have in common. When the congas roll and we both rise to dance, we laugh. Twinship make us comfortable.

Similarities open us up, and we reveal our unique personal histories. Everyone has a story of struggle and strength, and sharing them seals the friendship.

In the beginning, we have curiosity and clarifying conversations: “What did you mean by that?” We’re aware we grew up differently. No worries—we tune the radio to a common playlist and enjoy the ride.

Then the sun hits a certain point on the horizon, and we fail to notice the Illusion of Transparency settling over us. We finish one another’s sentences and pride ourselves in saying, “Shh. You don’t even have to say it. I know exactly how you feel.” We feel secure, having a friend who knows us inside and out.

It’s an illusion. Truly. The Illusion of Transparency is a cognitive bias just as much as Gambler’s Fallacy or Hindsight Bias. We do not know exactly how another person feels every single time, and it’s not justifiable to expect someone to behave according to our unwritten rules. Rather than recognize this, disappointment results in judgment, and resentment replaces curiosity and acceptance. It’s easy to miss what’s happened. After all, our unwritten rules are simply logic. They’re the way everyone should behave. Those who don’t do what we would are selfish or lazy or inconsiderate. That’s another cognitive bias, called Naïve Realism. You and I began developing individual standards when we were children, and we’ve been refining them all our lives. Nobody else has the same combination of experiences and personal interpretation.

We might get lucky hundreds of times. It’s logical to be lulled into thinking we’re exactly alike, because our BFF is often the person who’s done the right thing over and over again.

It’s a shock to be suddenly forced to talk through an issue, when the Illusion of Transparency has made everything feel easy. In an instant, we discover more differences. People who rarely have conflict rarely approach conflict the same way.

That’s uncomfortable.

It’s easy to walk away. Delete the phone number, unfollow the friend, move on. Social media tells us we’re smart to let go of toxic friends. Conflict feels toxic, so we raise a glass to freedom and set years of memories by the road.

Are we right? What is toxic?

Toxic relationships damage a person psychologically. They don’t just have occasional difficulties, they’re a constant drain on a person’s self-esteem. The toxic person is often manipulative and impossible to please.

Codependent relationships are those in which Person A keeps Person B from becoming strong by continually convincing Person B they can’t do anything without Person A. Often Person A thinks they’re helping.

Dr. Doris Jeannette has a terrific chart comparing healthy and unhealthy relationships. In a healthy relationship, she says, “You give energy freely, with no expectations, strings or conditions.” Healthy friendships often involve two people who share joys and struggles, deep talk and small talk. Sometimes one friend is struggling while another is celebrating, but that’s just the bumpy road of life.

Conflict is not toxicity. It is uncomfortable, and it might hamper our self-esteem until it’s resolved. I swear, conflict gives me hives on the inside of my skull. Silence feels kinder, but things like cancer and mold grow in silence. Silence is not kind.

Relational longevity offers such precious benefits, I’ve learned to embrace the tough discussions. I’m not great at it; sometimes I’m too enthusiastic to overcome a disagreement. Talking may not result in agreement. Two people, living two lives with two different brains, can have two different sets of feelings about a matter. That’s diversity, the celebration which started it all.

What’s the solution?

Curiosity. Candid, patient discussion. Love, acceptance and forgiveness. Love, Acceptance and Forgiveness is a fantastic book, by the way.

2 If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but do not have love, I am nothing.3 If I give all I possess to the poor and give over my body to hardship that I may boast, but do not have love, I gain nothing.

4 Love is patient, love is kind. It does not envy, it does not boast, it is not proud.5 It does not dishonor others, it is not self-seeking, it is not easily angered, it keeps no record of wrongs.6 Love does not delight in evil but rejoices with the truth.7 It always protects, always trusts, always hopes, always perseveres.